This research aims to examine the relationship between early behavioral development and heavy metal (mercury, lead, cadmium, nickel and manganese) levels in tissues of young Common Terns (Sterna hirundo), with the long term goal of elucidating mechanisms of heavy metal action on neurobehavioral development. Specific aims include 1) assessing differences in behavior during the hatching period and up to 3 days of age, 2) measuring heavy metal levels in the subjects, and 3) determining the statistical association and contributions of varations in the metal levels to the variance in the behavioral measures. Behavioral measures will include 1) time required for the hatching process, 2) behavioral thermoregulation measured by the latency required for shade seeking, 3) visual cliff response, and 4) development of normal food handling capabilities. These behavior patterns involve sensory and motor functions known or suspected of being adversely effected by heavy metals in birds and/or mammals, including humans. The research aims to develop behavioral measures that can be used experimentally to examine the toxic metal effects. The feasibility of using an avian model for examination of such mechanisms lies in the fact that birds, like humans, are primarily visual and acoustic in their social interactions, whereas communication in most laboratory mammals is primarily tactile and olfactory. Moreover, we will be conducting the study in the field under nearly natural conditions, and will be testing behaviors that are vital to survival and are normally developed under intense selection, early in life. In a colony of Common Terns nesting on Long Island, New York, thirty test subjects will be selected at random, tested over a three day period, and sacrificed for chemical analyses, which will be performed by the Environmental Toxicology Laboratory of the New Jersey State Department of Health. Factor analysis and discriminant analysis will be used to assess the contribution of metal levels to behavioral performance.